Older Adults With More Of This Were More Likely To Sleep Well
Picture a typical day: You open the curtains, make breakfast, work beside a window, and maybe step outside for a few minutes. It sounds like plenty of light, but most of the day may still be spent under indoor lighting.
And while a bright room can feel, well, bright, it doesn't come close to the intensity of outdoor daylight. Researchers wanted to know whether that difference matters for older adults, particularly when it comes to sleep and daily activity.
So, in a recent study, they tracked their light exposure, along with their sleep and movement, to see what patterns emerged.
About the study
The ENLIGHTENme study included 202 adults ages 63 to 92 living independently in Amsterdam, Bologna, and Tartu.
For two weeks, participants wore a wrist device that tracked their sleep and activity and a small sensor around their neck that measured the light reaching them throughout the day.
This allowed researchers to see how much light people were actually exposed to, rather than relying on estimates of how much time they spent outdoors.
Researchers then looked at participants' usual light exposure and divided them into three groups: low, moderate, and high.
Separately, 98 participants were given a light therapy lamp to use at home for 12 weeks, while 93 participants continued without the lamp.
The researchers were interested in how everyday light exposure related to sleep and activity, as well as whether the timing of supplemental light affected daily rhythms.
Your circadian rhythm is your body's internal 24-hour clock, which helps coordinate sleep and wakefulness.
More daytime light was linked to better sleep
The clearest pattern showed up when researchers compared people based on their usual light exposure.
Older adults in the low-light group were less active during the day and had fewer stretches of consolidated wakefulness, meaning their periods of being awake were more broken up. They also reported poorer sleep quality.
People in the high-light group were three times as likely to fall into the healthy range on a standard sleep-quality questionnaire compared with those in the low-light group. The moderate-light group didn't show the same significant difference.
Importantly, these groups were based on participants' everyday light exposure, not on whether they received the light therapy lamp.
So the finding isn't that people who used the lamp slept better. It was an association between getting more light during daily life and having better sleep.
The type and timing of that light matter, too.
Outdoor daylight is far brighter than typical indoor lighting, and researchers found that people with metabolic conditions such as high blood pressure, diabetes, obesity, or cardiovascular disease generally had lower overall light exposure and spent less time in brighter, daylight-level light.
The timing of light may matter, too
The lamp portion of the study offered another clue. Participants were told to use their lamp within an hour of waking, not before sunrise, and turn it off at least four hours before their usual bedtime.
Not everyone followed those instructions consistently. Among the people who did use the lamp, researchers found that those who started earlier in the day tended to have less disrupted daily rest-activity patterns.
This association remained after researchers accounted for whether someone naturally tended to be more of a morning or evening person.
Why does timing matter? Light is one of the main signals your body clock uses to keep track of the day. Bright light during the daytime helps reinforce that signal, while too much bright light late in the evening can make the transition toward sleep more difficult.
That daytime signal may also become harder to receive with age. Changes in the eyes can reduce the amount of light reaching the systems that regulate the body clock, particularly shorter-wavelength, blue-range light.
A few ways to get more daylight
You don't need to turn your home into a light therapy clinic to make the most of these findings. Start with the light that's already outside your door.
- Get outside earlier: Have your morning coffee on the patio, take a walk, or spend a few minutes outdoors before settling into work.
- Choose daylight when you can: Sitting near a window is useful, but stepping outside gives you a much brighter dose of light.
- Give your evenings a softer landing: Keep indoor lighting gentler as bedtime approaches rather than surrounding yourself with bright light late into the night.
- Think about timing: If you use a light therapy lamp, follow the manufacturer's guidance and speak with a health professional if you're unsure about when or how to use it.
The takeaway
Older adults who naturally got more daytime light tended to have better sleep and more consistent daily activity patterns.
The study also suggests that getting supplemental light earlier in the day may help support a steadier body clock.
